Recording artist Britney Spears arrives at the Clive Davis and Recording Academy Pre Grammy Gala and Salute to Industry Icons in Beverly Hills, California February 11, 2012.[Photo/Agencies]

Britney Spears is close to signing a "$12-15 million deal" to join the US 'X Factor'.

The 'Hold It Against Me' hitmaker is wanted by show boss Simon Cowell to replace Nicole Scherzinger and Paula Abdul on the panel of the musical TV series, but negotiations are currently sticking about how many seasons she would have to work on.

A source told HollywoodLife.com: "Money is not an issue for the show. As of now, they are looking to pay her $12-15 million for the first season, with a drastic price hike for a second year based on ratings performance.

"Simon Cowell wants at least a two-year commitment and Britney wants an out clause if she doesn't want to continue after one year of service."

Both Simon and fellow judge L.A. Reid are staying in their judging seats for the show, which experienced lower than expected ratings after it was unveiled for the first time in the US last year.

In addition to Britney, Simon is also keen to have British singer Adele join the panel.

A source said: "Simon is always looking for new directions and ideas.

"He thinks Adele's success and achievements are incredible. True musicianship and a serious approach can bring a lot of credibility and an extra dimension to his show."